A virtual machine is a software construct that creates a virtualized environment between a computing system such as a server and an operating system, enabling software operation on an abstract or virtual machine.
One problem with virtual machines is that a server running multiple virtual machines has multiple operating systems. A substantial portion of the total cost of ownership (TCO) of a server is spent in ongoing maintenance and management of the operating systems.
Management of multiple operating systems is typically assisted by tools that simplify administration of servers or groups of servers and the operating systems executing in the servers. Such tools enable synchronization of files and logs as well as command fan-out capabilities. Other tools enable a user to maintain a large number of servers from a central location.